BCECE Engineering BCECE Engineering Solved Paper-2001

  • question_answer
    The number of solutions of equations \[x+y-z=0,3x-y-z=0,x-3y+1=0\]is:

    A)  0                                            

    B)  1                            

    C)  2                            

    D)         infinite

    Correct Answer: D

    Solution :

    Key Idea: If system of equations is a homogeneous equation and its determinant is zero, then the solution of the given equation is infinitely. Given system of equations are\[~x+y-\text{ }z=0,\]  and \[3x\text{ }-\text{ }y\text{ }-\text{ }z=0\] Now,     \[\Delta =\left| \begin{matrix}    1 & 1 & -1  \\    3 & -1 & -1  \\    1 & -3 & 1  \\ \end{matrix} \right|\]                 \[=1(-1-3)-1(3+1)-1(-9+1)\] \[=-4-4+8=0\] \[\therefore \] It has infinite solution. Note: It\[\Delta \ne 0,\] then the only solution is \[x=y=z=0.\]


You need to login to perform this action.
You will be redirected in 3 sec spinner